MD022 - Headers should be surrounded by blank lines

Tags: headers, blank_lines

Aliases: blanks-around-headers

This rule is triggered when headers (any style) are either not preceded or not followed by a blank line:

# Header 1
Some text

Some more text
## Header 2

To fix this, ensure that all headers have a blank line both before and after (except where the header is at the beginning or end of the document):

# Header 1

Some text

Some more text

## Header 2

Rationale: Aside from aesthetic reasons, some parsers, including kramdown, will not parse headers that don't have a blank line before, and will parse them as regular text.

MD005 - Inconsistent indentation for list items at the same level

Tags: bullet, ul, indentation

Aliases: list-indent

This rule is triggered when list items are parsed as being at the same level, but don't have the same indentation:

* Item 1
    * Nested Item 1
    * Nested Item 2
   * A misaligned item

Usually this rule will be triggered because of a typo. Correct the indentation for the list to fix it:

* Item 1
  * Nested Item 1
  * Nested Item 2
  * Nested Item 3

MD005 - Inconsistent indentation for list items at the same level

Tags: bullet, ul, indentation

Aliases: list-indent

This rule is triggered when list items are parsed as being at the same level, but don't have the same indentation:

* Item 1
    * Nested Item 1
    * Nested Item 2
   * A misaligned item

Usually this rule will be triggered because of a typo. Correct the indentation for the list to fix it:

* Item 1
  * Nested Item 1
  * Nested Item 2
  * Nested Item 3

MD006 - Consider starting bulleted lists at the beginning of the line

Tags: bullet, ul, indentation

Aliases: ul-start-left

This rule is triggered when top level lists don't start at the beginning of a line:

Some text

  * List item
  * List item

To fix, ensure that top level list items are not indented:

Some test

* List item
* List item

Rationale: Starting lists at the beginning of the line means that nested list items can all be indented by the same amount when an editor's indent function or the tab key is used to indent. Starting a list 1 space in means that the indent of the first nested list is less than the indent of the second level (3 characters if you use 4 space tabs, or 1 character if you use 2 space tabs).

MD022 - Headers should be surrounded by blank lines

Tags: headers, blank_lines

Aliases: blanks-around-headers

This rule is triggered when headers (any style) are either not preceded or not followed by a blank line:

# Header 1
Some text

Some more text
## Header 2

To fix this, ensure that all headers have a blank line both before and after (except where the header is at the beginning or end of the document):

# Header 1

Some text

Some more text

## Header 2

Rationale: Aside from aesthetic reasons, some parsers, including kramdown, will not parse headers that don't have a blank line before, and will parse them as regular text.

MD002 - First header should be a top level header

Tags: headers

Aliases: first-header-h1

Parameters: level (number; default 1)

This rule is triggered when the first header in the document isn't a h1 header:

## This isn't a H1 header

### Another header

The first header in the document should be a h1 header:

# Start with a H1 header

## Then use a H2 for subsections

MD032 - Lists should be surrounded by blank lines

Tags: bullet, ul, ol, blank_lines

Aliases: blanks-around-lists

This rule is triggered when lists (of any kind) are either not preceded or not followed by a blank line:

Some text
* Some
* List

1. Some
2. List
Some text

To fix this, ensure that all lists have a blank line both before and after (except where the block is at the beginning or end of the document):

Some text

* Some
* List

1. Some
2. List

Some text

Rationale: Aside from aesthetic reasons, some parsers, including kramdown, will not parse lists that don't have blank lines before and after them.

Note: List items without hanging indents are a violation of this rule; list items with hanging indents are okay:

* This is
not okay

* This is
  okay

MD006 - Consider starting bulleted lists at the beginning of the line

Tags: bullet, ul, indentation

Aliases: ul-start-left

This rule is triggered when top level lists don't start at the beginning of a line:

Some text

  * List item
  * List item

To fix, ensure that top level list items are not indented:

Some test

* List item
* List item

Rationale: Starting lists at the beginning of the line means that nested list items can all be indented by the same amount when an editor's indent function or the tab key is used to indent. Starting a list 1 space in means that the indent of the first nested list is less than the indent of the second level (3 characters if you use 4 space tabs, or 1 character if you use 2 space tabs).

MD009 - Trailing spaces

Tags: whitespace

Aliases: no-trailing-spaces

Parameters: br_spaces (number; default: 0)

This rule is triggered on any lines that end with whitespace. To fix this, find the line that is triggered and remove any trailing spaces from the end.

The brspaces parameter allows an exception to this rule for a specific amount of trailing spaces used to insert an explicit line break/br element. For example, set brspaces to 2 to allow exactly 2 spaces at the end of a line.

Note: you have to set brspaces to 2 or higher for this exception to take effect - you can't insert a br element with just a single trailing space, so if you set brspaces to 1, the exception will be disabled, just as if it was set to the default of 0.

MD025 - Multiple top level headers in the same document

Tags: headers

Aliases: single-h1

Parameters: level (number; default 1)

This rule is triggered when a top level header is in use (the first line of the file is a h1 header), and more than one h1 header is in use in the document:

# Top level header

# Another top level header

To fix, structure your document so that there is a single h1 header that is the title for the document, and all later headers are h2 or lower level headers:

# Title

## Header

## Another header

Rationale: A top level header is a h1 on the first line of the file, and serves as the title for the document. If this convention is in use, then there can not be more than one title for the document, and the entire document should be contained within this header.

Note: The level parameter can be used to change the top level (ex: to h2) in cases where an h1 is added externally.

The underlying implementation of String::replaceAll calls the java.util.regex.Pattern.compile() method each time it is called even if the first argument is not a regular expression. This has a significant performance cost and therefore should be used with care.

When String::replaceAll is used, the first argument should be a real regular expression. If it’s not the case, String::replace does exactly the same thing as String::replaceAll without the performance drawback of the regex.

This rule raises an issue for each String::replaceAll used with a String as first parameter which doesn’t contains special regex character or pattern.

Noncompliant Code Example

String init = "Bob is a Bird... Bob is a Plane... Bob is Superman!";
String changed = init.replaceAll("Bob is", "It's"); // Noncompliant
changed = changed.replaceAll("\\.\\.\\.", ";"); // Noncompliant

Compliant Solution

String init = "Bob is a Bird... Bob is a Plane... Bob is Superman!";
String changed = init.replace("Bob is", "It's");
changed = changed.replace("...", ";");

Or, with a regex:

String init = "Bob is a Bird... Bob is a Plane... Bob is Superman!";
String changed = init.replaceAll("\\w*\\sis", "It's");
changed = changed.replaceAll("\\.{3}", ";");

See

• {rule:java:S4248} - Regex patterns should not be created needlessly